This invention claims priority of a German filed patent application 199 49 005.8, which is incorporated by reference herein.
The invention concerns a device for delivering various substrates into a high-precision measuring instrument. In particular, the invention concerns a device which comprises a magazine in which are configured several compartments in which substrate holders for different substrates can be deposited.
The invention further concerns a method for delivering various substrates into a high-precision measuring instrument.
U.S. Pat. No. 5,026,239 describes a mask cassette and a loading mechanism for the mask cassette. A plurality of masks are stored in a mask cassette that can be sealed off from ambient air. The mask cassette is initially located in a mask chamber that communicates through a small opening with a main chamber. Both chambers are hermetically sealed toward the outside. In the mask chamber, the mask cassette is opened and is correspondingly brought into position so that a gripping and transport apparatus can access the individual masks. The masks are taken by the gripping and transport apparatus, through the small opening, into the main chamber, and there correspondingly exposed. The exposure in the present exemplary embodiment is with X-rays, so that both chambers must be evacuated for purity reasons.
A system for mask measurement is published in SPIE Vol. 3096; 0277-786X/97 (pp. 433 to 444). The system comprises an automatic loading apparatus for various substrate types. The various substrates are located in slide-in compartments in a magazine. Also provided is a magazine that possesses, above a turntable, three compartments, in each of which different substrate holders are deposited. The disadvantage of this system is that contaminants can occur as a result of the movable slide-in compartments, and can settle onto the substrates and thus disadvantageously influence the reproducibility of the measurement.
It is therefore the object of the invention to create a device with which the reproducibility of the measurement results can be greatly improved. It is intended by way of the present invention to alleviate the shortcomings of the existing art, for example the settling of particles on the substrates as the compartments of the magazine are moved, and to achieve a simplification of substrate handling for the operator and monitoring of thermal equilibrium.
In the case of a device of the kind cited initially, this object is achieved according to the present invention by a device comprising a magazine which defines several compartments in which substrate holders for various substrates can be deposited, a loading station in which the substrate holders can be loaded with the substrate that matches the substrate holder, and an automatic transfer device that removes substrate holders from the magazine and introduces them into the loading station, or removes the substrate holders together with the introduced substrate from the loading station.
A further object of the invention is to create a method with which substrates that are to be measured can be loaded into a high-precision measuring instrument, maximum reproducibility of the measurement results being guaranteed.
This object is achieved, in a method of the kind cited initially, in that the method comprises the following steps:
loading a specific substrate holder into the loading station;
introducing into the loading station a substrate type that matches the substrate holder;
checking conformity between the loaded substrate holder and introduced substrate type;
picking up the substrate in the substrate holder by way of the transport device; and
transferring the picked-up substrate holder, together with the loaded substrate, into the high-precision measuring instrument.
Advantageous developments are evident from the features of the dependent claims.
With the configuration according to the present invention of the measuring instrument known per se, it becomes possible to eliminate those aspects that in the past led to problems. (These related, for example, to particle deposits on the substrates upon insertion of the drawers into the magazine, since without xe2x80x9cstoppersxe2x80x9d the drawers could easily be pulled out. The storage compartments for the substrates were fairly tight; with larger substrates, it was very difficult to introduce the substrates by hand, or it was impossible to monitor whether a substrate was already present in a compartment.)
In order to ensure a reliable loading procedure, loading of the substrate holders is accomplished only via the loading station. In order to facilitate the operator""s work in this context, the loading station is mounted at an ergonomic height of approx. 90-95 cm. The operator places the substrate onto the frame-shaped substrate holder inside the loading station. The support surfaces of the substrate holder for the substrate can be of very small dimensions, since the substrate is loaded entirely automatically onto the substrate holder. A magazine is loaded, exclusively with the aid of a robot arm, with the substrate holder including the substrates placed on it. There are no longer any drawers, preventing any further generation of particles that might contaminate the substrates in the compartments of the magazine. In addition, the possibility exists of integrating automatic loading from a carrier.